This invention relates to the preparation of aryl carbonyl compounds, and in particular to para substituted aryl carbonyl compounds.
Aryl carbonyl compounds are useful in the preparation of poly(arylene ether ketones). In the preparation of these polymers it is essential that the monomers used be in a highly pure state to prevent undesirable side reactions. Furthermore, the polymers obtained should be stable enough to survive extrusion without undue deleterious effects on their physical properties. The substitution pattern of the monomers used can control the properties of the polymers synthesised, and it is generally recognized that the highest melting points and glass-rubber transition temperatures are obtained with all para linked polymers. Mixtures of substitution isomers are used when polymers of reduced crystallinity or lowered Tg are required, but the all para substituted polymers are most preferred. When mixtures of monomers are used, known ratios of the different isomers are needed, necessitating the use of pure starting materials. The present invention relates to a process for the preparation of aryl carbonyl compounds that improves outstandingly the degree of purity of the product and/or the degree of para substitution.
Aryl carbonyl compounds are also useful as chemicals and chemical intermediates, for example, in the pharmaceutical and agricultural chemicals, dyestuffs and general chemical additives area. Here too it is frequently found that the all para substituted carbonyl compounds are the most useful. Avoidance of concurrent formation of other isomeric byproducts in the synthesis of such compounds is always beneficial economically and in some instances is essential because some isomeric compounds which are difficult to remove have been found to be toxic or even carcinogenic.